The present invention relates generally to closure devices and, more particularly, to interlocking fastening strips that are occluded and deoccluded by a slider. The inventive closure devices may be employed in traditional fastener areas, and is particularly well suited for fastening flexible storage containers, including plastic bags.
The use of closure devices for fastening storage containers, including plastic bags, is generally well known. Furthermore, the manufacture of closure devices made of plastic materials is generally known to those skilled in the art, as demonstrated by the numerous patents in this area.
A particularly well-known use for closure devices is in connection with flexible storage containers, such as plastic bags. In some instances, the closure device and the associated container are formed from thermoplastic materials, and the closure device and the side walls of the container are integrally formed by extrusion as a single piece. Alternatively, the closure device and side walls of the container may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. In either event, such closure devices are particularly useful in providing a closure means for retaining matter within the bag.
Conventional closure devices typically utilize mating fastening strips or closure elements which are used to selectively seal the bag. With such closure devices, however, it is often difficult to determine whether the fastening strips are fully occluded. This problem is particularly acute when the strips are relatively narrow. Accordingly, when such fastening strips are employed, there exists a reasonable likelihood that the closure device is at least partially open.
Such fastening strips devices are also particularly difficult to handle by individuals with limited manual dexterity. Thus, in order to assist these individuals and for ease of use by individuals with normal dexterity, the prior art has also provided sliders for use in opening and closing the fastening strips, as disclosed, for example, in U.S. Pat. Nos. 4,199,845, 5,007,142, 5,007,143, 5,010,627, 5,020,194, 5,070,583, 5,283,932, 5,301,394, 5,426,830, 5,431,760, 5,442,838, and 5,448,808. Many of these sliders include a separator which extends at least partially between the fastening strips. When the slider is moved in an appropriate direction towards one end of the fastening strips, the separator divides the fastening strips and opens the bag. Once the fastening strips are separated, the fastening strips can be relocked if desired by moving the slider in the opposite direction toward the other end of the fastening strips to reclose the bag.
One problem associated with using sliders is that the slider can cause the bags to leak. In particular, the separator of the slider can cause an unoccluded gap between the fastening strips when the slider is at the end of the bag when the bag is supposed to be fully closed. The gap may allow the bag to leak. Leaky bags are a disadvantage in many of the applications of closable plastic bags. For example, leaky bags will not store liquids unless the bag is properly oriented. Leaky bags can often cause a mess and/or damage to other items when liquids leak from the bags. If the bags are used for foods for refrigerator storage, leaky bags will communicate air in and out of the bag which can cause premature spoilage of the food inside the bag or the contents in the bag can undesirably generate an odor into the air inside the refrigerator.
The inventive leak-proof closure device is intended for use with a storage container which includes a pair of complementary sheets or opposing flexible side walls, such as a plastic bag. The closure device includes interlocking fastening strips disposed along respective edge portions of the opposing side walls, and a slider slidably disposed on the interlocking fastening strips. The slider facilitates the occlusion of the fastening strips when moved towards a first end thereof. The slider includes a separator that facilitates the deocclusion of the fastening strips when moved towards a second end thereof. The fastening strips are sealingly secured together at the first and second ends to prevent leakage from the container or bag. In accordance with the present invention, a second seal is provided in proximity to the first end that fixes the fastening strips together. The second seal prevents the formation of a gap at the first end by the separator when the fastening strips are fully closed and to thereby provide a leak-proof container.
According to an aspect of one embodiment, the second seal and the seals at the first and second ends are accomplished by heat sealing, ultrasonic sealing or other similar process that melts the plastic material of the fastening strips together. This may be accomplished in one heat sealing operation. In one embodiment, there is an unmelted portion between the second seal and the first end to prevent the slider from being removed from the fastening strips in the vertical Z axis from the first end.
These and other features and advantages of the present invention will become more readily apparent upon reading the following detailed description of exemplified embodiments and upon reference to the accompanying drawings herein.